Mechanism for automatically blocking a lifting roller in venetian blinds



May 14, 1963 H. FABER 3,

MECHANISM FOR AUTOMATICALLY BLOCKING A LIFTING ROLLER I ENETIAN BLINDSFiled June 1960 INVENTOR HARRY FABER BY W.

ATTORNEY.

llnite States arent Patented May 14, 1963 ice 3,089,664 MECHANISM FORAUTOMATICALLY BLOCKING A LIFTING ROLLER IN VENETIAN BLINDS Harry Faber,Ryslinge, Denmark, assignor to A/S Chr.

Fabers Fabriker, Ryslinge, Denmark Filed June 16, 196i), Ser. No. 36,553

Claims priority, application Denmark June 19, 1959 2 Claims. (Cl.2.4299) My invention relates to a mechanism for automatically blocking aroller for a lifting cord or a lifting band in a Venetian blind.

In many cases the raising of a blind is eiiected in the way that two ormore lifting cords or lifting bands are connected with the bottom railof the blind, and from there are passed upwards through apertures in theindividual blind slats, placed vertically one above another, and in thehead rail of the blind are passed over a corresponding number ofrollers, on which the cords or bands are wound, and which are positionedon a common horizontal shaft, which is mounted in the head rail and bysome operating mechanism rotated in one direction or the other to effectraising and lowering, respectively, of the blind.

When Venetian blinds are lowered, especially larger ones, as e.-g. thoseused for shop windows, it may happen that the bottom rail of the blindstrikes against an obstruction, so that one or more of the cords orbands are relieved of their weight and by continued unwinding from thelifting roller become entangled with other things or with themselves orare otherwise disarranged. This is especially so, when steel cords orsteel bands, which among other things may easily kink, are used forraising the blind.

Attention has already before been fixed on this problem, and severalsecuring mechanisms have been suggested in the form of blocking members,which operate when the cords or bands are relieved and arrest thecontinued lowering movement of the lifting roller. Such blocking membershave been brakes or stops, which are kept in inactive position by thetight cord or the tight band, but are put into active position under theinfluence of a compression spring or a tension spring when the cord orband is relieved, and prevent a continued movement of the roller in thelowering direction, until the obstruction, which caused the cord or theband to be relieved, has been removed, and the cord or band againtightens.

The said known securing mechanisms have proved to possess thesubstantial disadvantage that they are not operationally reliable onaccount of the springs used, which partly are exposed to damage, partlylose their spring power in the course of time or because of deposits ofdirt.

The primary object of the present invention is to remedy the abovementioned drawback by providing a mechanism, which is so positioned thatit is not exposed to damage. Another object is to provide a mechanismwhich preserves its operational reliability irrespective of the passingof time.

Still another object is to provide a reliable mechanism, in which theforce necessary to move the blocking member into its active position isalways present in the form of the own weight of the member.

A further object of my invention is to provide a mechanism including ablocking member which is well and safely guided in its movements.

A still further object is to provide a mechanism which is well protectedagainst dirt and damage.

Other objects of my invention will appear from the following descriptiontaken in conjunction with the accompanying drawings, which describe andshow my invention by way of illustration.

In the drawing,

FIGURE 1 is a side elevation of a mechanism embodying a preferred formof my invention, with the blocking member in its inactive position,

FIGURE 2 is a similar side elevation, but with the blocking member inits active position, and

FIGURE 3 is an enlarged sectional view on the lines III'III of FIGURE 2.

Between two transverse walls 2 and 4, which are fixedly positioned in ahead rail '5 of a Venetian blind, there is disposed a roller 6 for alifting cord or a lifting band, such as a steel band 8. This band isattached below to the bottom rail of the blind, not shown, and is passedup through apertures in the blind slats, not shown, and through anaperture 9 in the bottom of the head rail 5 into the space between thepartitions 2 and 4, where it is wound on the roller 6, which is fixedlydisposed on a longitudinal shaft, such as a hexagonal shaft 10, by therotation of which the blind can thus be raised and lowered.

The roller 6 has an annular recess 12., which is open towards the plate2, and wherein a blocking member 14 with arched lateral arms 16 and 18is loosely disposed, said arms having a certain radial clearance in therecess 12. The blocking member 14 is locked against movement in theperipheral direction of the roller 6 by means of a projection Ztl, whichis radially displaceable in an aperture 22 in the surface of the roller6. Furthermore, the blocking member 14 has a stop 24, protruding in theaxial direction of the roller 6. The plate 2 is provided with a centralopening 26, which has such a size and shape that the roller 6 with theblocking member 14 and the stop 24, provided thereupon, may freelycomplete a full rotation, when the blocking member 14 is in theinnermost position shown in FIG. 1. When on the contrary the blockingmember occupies the outermost position shown in FIGS. 2 and 3, the stop24 will strike against a radial facing or ledge 28 at the outermost edgeof the aperture 26 and thereby prevent a continued rotation of theblocking member 14- and consequently of the roller 6.

The mechanism works as follows. During normal lowering of the blind withthe band tightened as shown in FIG. 1 by anticlockwise rotation of theshaft 10, the band 8 which is tightly wound on the roller 6 will forcethe projection 20 inwards and thereby keep the blocking member 14 withthe stop 24 in its innermost position, shown in FIG. 1, whereby theblocking member 14 is rotated together with the roller 6, the stop beingunobstructed in its rotation. If the part of the bottom rail of theblind, which is carried by the band 8, strikes against any obstructionduring the lowering, the band 8 is relieved, and this relief isimmediately transmitted to the windings on the roller 6, which on thelowermost side of the roller 6 move away from its surface. When,therefore, during its rotation with the roller 6 the blocking member 14for the first time following arrives in its lowermost position as shownin FIGS. 2 and 3, it will by its own weight fall down into its outermostposition, in which the stop 24 will strike the ledge 28 and therebyprevent a continued rotation of the roller 6 and consequently of theshaft 10, so that the operators attention is turned to the obstruction,which can be removed, and thereafter without hindrance the roller 6may-if necessary after having been turned slightly back in order totighten the band 8 and the abutment of the band windings against theroller-be turned again in the direction corresponding to lowering, theblocking member being then forced into its inactive position as shown inFIG. 1.

The mechanism according to the invention also operates to prevent acontinued rotation of the shaft 10 and consequently of the roller 6,when the bottom rail of the blind has arrived in its lowermost position,which may be determined by a window sill or a floor under the window orby the length of the ladder tape of the blind, in which case the band 8is also relieved. The mechanism may be placed at each of the liftingrollers of the blind or at one or several thereof, preferably the twooutermost rollers on the blind.

Even if the mechanism according to the invention is of particularimportance for larger Venetian blinds, e.g. blinds for shop windows,where it is often impossible from the place of operation to watch themovement of the blind during lowering, it is also with great advantageuseful for smaller blinds, where obstructions in the lowering path ofthe blind may as well occur, which may disarrange the lifting band.

The mechanism according to my invention may be altered in many wayswithout departing from the invention. Thus, it is not necessary that thelifting roller be positioned between transverse walls, one of whichforms the facing for the stop on the blocking member, but said stop maybe arranged to cooperate with any other suitable fixed facing. Theblocking member may also have a shape and position different from thoseshown in the drawing. The main thing is that the blocking member solelyby the action of its own Weight can move into its active blockingposition. It is natural that the blocking member should have a certainweight, but precisely this fact in connection with the very simpleconstruction produces a robust mechanism, which will stand undamagedeven the roughest treatment, to which a Venetian blind may be exposed inoperation.

It is to be understood that various other modifications and departuresfrom the construction described may be made; and I do not wish in anyway to limit myself to the exact details and mode of operation set forthin this specification and drawing, for it will be obvious that widedeparture may be made without departing from the spirit and scope of myinvention as set forth in the appending claims.

I claim as my invention:

1. In a mechanism for automatically blocking a roller for a lifting bandof a Venetian blind, comprising a lifting band, at least one facingmember, a roller positioned in said facing member and having a circularrecess in one of its ends, a fixed stop on said facing member, ablocking member displaceable inwardly by said band when wound on saidroller and in outwardly radial direction with respect to said roller tocooperate with said fixed stop when the band is relieved, and slidablymovable into blocking position solely by the action of its own weight,said blocking member being loosely disposed with a certain radialclearance with respect to said roller in said recess and positionedbeneath the surface of said roller face, said recess being shaped as acircular arc and being concentrical with the axis of said roller, andlateral arms shaped as circular axis on said blocking member and havinga. projection guided in an aperture in the roller face, a stop on theblocking member protruding in the axial direction of the roller, saidlast mentioned stop striking against said fixed stop in the outermostposition of the blocking member clear of the same in the innermostposition thereof.

2. In a mechanism according to claim 1, said facing member comprising aradial ledge on the lowermost part of an otherwise circular outermostedge of an opening in said facing member and said facing member abuttingon one end face of the roller.

References Cited in the file of this patent UNITED STATES PATENTS 43,294Dalton June 28, 1864 2,071,941 Flaws Feb. 23, 1937 2,105,469 Bosch Jan.18, 1938 2,954,940 Herrrnann Oct. 4, 1960 2,982,492 Spielman May 2, 19612,990,131 Carlsson June 27, 1961

1. IN A MECHANISM FOR AUTOMATICALLY BLOCKING A ROLLER FOR A LIFTING BANDOF A VENETIAN BLIND, COMPRISING A LIFTING BAND, AT LEAST ONE FACINGMEMBER, A ROLLER POSITIONED IN SAID FACING MEMBER AND HAVING A CIRCULARRECESS IN ONE OF ITS ENDS, A FIXED STOP ON SAID FACING MEMBER, ABLOCKING MEMBER DISPLACEABLE INWARDLY BY SAID BAND WHEN WOUND ON SAIDROLLER AND IN OUTWARDLY RADIAL DIRECTION WITH RESPECT TO SAID ROLLER TOCOOPERATE WITH SAID FIXED STOP WHEN THE BAND IS RELIEVED, AND SLIDABLYMOVABLE INTO BLOCKING POSITION SOLELY BY THE ACTION OF ITS OWN WEIGHT,SAID BLOCKING MEMBER BEING LOOSELY DISPOSED WITH A CERTAIN RADIALCLEARANCE WITH RESPECT TO SAID ROLLER IN SAID RECESS AND POSITIONEDBENEATH THE SURFACE OF SAID ROLLER FACE, SAID RECESS BEING SHAPED AS ACIRCULAR ARC AND BEING CONCENTRICAL WITH THE AXIS OF SAID ROLLER, ANDLATERAL ARMS SHAPED AS CIRCULAR AXIS ON SAID BLOCKING MEMBER AND HAVINGA PROJECTION GUIDED IN AN APERTURE IN THE ROLLER FACE, A STOP ON THEBLOCKING MEMBER PROTRUDING IN THE AXIAL DIRECTION OF THE ROLLER, SAIDLAST MENTIONED STOP STRIKING AGAINST SAID FIXED STOP IN THE OUTERMOSTPOSTION OF THE BLOCKING MEMBER CLEAR OF THE SAME IN THE INNERMOSTPOSITION THEREOF.